Utahraptor
| Utahraptor Temporal range: Early Cretaceous,
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| Genus: | Utahraptor |
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U. ostrommaysorum Kirkland, Gaston, & Burge, 1993 (type) | |
Utahraptor (meaning "Utah's predator")[1] is the largest known member of the theropod dinosaur family Dromaeosauridae, and dates from the upper Barremian stage of the early Cretaceous period (about 126 million years ago).[1]
Description
The holotype of Utahraptor is fragmentary, consisting of skull fragments, a tibia, claws and some caudal (tail) vertebra. The few elements suggest an animal about twice the size of Deinonychus.[1] Like other dromaeosaurids, Utahraptor had a huge curved claw on the second toe; one is preserved at 22 centimetres (8.7 inches) in length and is thought to reach 24 centimetres (9.4 inches) restored. The largest described specimens are estimated to have reached up to 7 m (23 ft) long and somewhat less than 500 kg (1,100 lb) in weight, equivalent to the Grizzly bear in size.[2][1] Some undescribed specimens in the BYU collections may have reached up to 11 m (36 ft) long, though these await more detailed study.[3]
It is thought that Utahraptor may be closely related to the smaller Dromaeosaurus and the giant Mongolian dromaeosaurid Achillobator.[1][4]
Although feathers have never been found in association with Utahraptor, there is strong phylogenetic evidence suggesting that all dromaeosaurids possessed them. This evidence comes from phylogenetic bracketing, which allows paleontologists to infer traits that exist in a clade based on the existence of that trait in a more basal form. The genus Microraptor is one of the oldest known dromaeosaurids, and is phylogenetically more primitive than Utahraptor.[5] Since Microraptor possessed feathers, it is reasonable to assume that this trait was present in all of Dromaeosauridae. Feathers were very unlikely to have evolved more than once in dromaeosaurs, so assuming that Utahraptor lacked feathers would require positive evidence that it did not have them.[6] So far, there is nothing to suggest that feathers were lost in larger, more derived species of dromaeosaurs.[7]
Discovery
James Kirkland, Robert Gaston, and Donald Burge discovered Utahraptor in 1991 in Grand County, Utah, within the Yellow Cat and Poison Strip members of the Cedar Mountain Formation.[1] Radiometric dating has shown that these parts of the Cedar Mountain Formation were deposited about 126 million years ago.[8] The type specimen is currently housed at the College of Eastern Utah Prehistoric Museum, although Brigham Young University currently houses the largest collection of Utahraptor fossils.
The type species (and only known species of Utahraptor), Utahraptor ostrommaysorum, was named for the American paleontologist John Ostrom, from Yale University's Peabody Museum of Natural History, and Chris Mays, of Dinamation International. Sculptor Raymond Persinger was included in James Kirkland's original abstract referencing Mr. Persinger's concepts regarding the claw structure.
In popular culture
The novel Raptor Red, by Robert Bakker, tells the story of a Utahraptor from the perspective of the animal. Other speculative reconstructions of Utahraptor lifestyle and behavior were presented in the BBC television series Walking with Dinosaurs and the History series Jurassic Fight Club. Both of the television series portrayed Utahraptor as almost completely featherless (apart from a small crest of feather spikes on their heads), and the History series contained further anatomical inaccuracies including pronated hands. Walking with Dinosaurs also featured it in Europe when the only fossils of Utahraptor have been found in America. (But this may not be inacurate, because as the book says, Europe and North America were together at this time.{for more information, see Asiamerica})A Utahraptor is one of the main characters in the webcomic Dinosaur Comics. This Utahraptor appears without feathers. Two Utahraptor appear as villains in The Land Before Time XI: Invasion of the Tinysauruses. The Paul Zindel novel Raptor features an evolved species of featherless Utahraptor living in a system of caves in present-day Utah.
References
- ^ a b c d e f Kirkland, J.I., Burge, D., and Gaston, R. (1993). "A large dromaeosaur [Theropoda] from the Lower Cretaceous of Utah." Hunteria, 2(10): 1-16.
- ^ Holtz, Thomas R. Jr. (2008) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages Supplementary Information
- ^ Britt, Chure, Stadtman, Madsen, Scheetz and Burge, (2001). "New osteological data and the affinities of Utahraptor from the Cedar Mountain Fm. (Early Cretaceous) of Utah." Journal of Vertebrate Paleontology, 21(3): 36A.
- ^ Turner, Alan H. (2007). "A basal dromaeosaurid and size evolution preceding avian flight". Science. 317 (5843): 1378–1381. doi:10.1126/science.1144066. PMID 17823350.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Xu, X., Zhou, Z., Wang, X., Kuang, X., Zhang, F. and Du, X. (2003). "Four-winged dinosaurs from China." Nature, 421(6921): 335-340, 23 Jan 2003. http://www.nature.com/nature/journal/v421/n6921/full/nature01342.html
- ^ Prum, R. & Brush A.H. (2002). "The evolutionary origin and diversification of feathers". The Quarterly Review of Biology 77: 261–295. doi:10.1086/341993.
- ^ Turner, A.H.; Makovicky, P.J.; Norell, M.A. (2007). "Feather quill knobs in the dinosaur Velociraptor". Science 317 (5845): 1721. doi:10.1126/science.1145076. PMID 17885130.
- ^ Kirkland, J.I. and Madsen, S.K. 2007. The Lower Cretaceous Cedar Mountain Formation, eastern Utah: the view up an always interesting learning curve. Fieldtrip Guidebook, Geological Society of America, Rocky Mountain Section. 1-108 p.
